CK-666 is a potent, selective and reversible inhibitor of ARP2/3 complex (actin related proteins 2 and 3) with an IC50 = 4 μM for human ARP2/3. Blocks actin nucleation and radically alters lamellipodial actin architecture, suspended cell shape and the cell spreading process. CK-666 attenuates BBB dysfunction induced by methamphetamine. A key new tool for studying actin assembly and the diverse range of actin-related processes in normal and pathophysiology. MW: 296.3. Purity ≥98% by TLC